Update changelog for 6.0.9

Author: kitchen-porter

CHANGELOG.md

@@ -5,7 +5,7 @@ This file is used to list changes made in each version of the transmission cookb
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## Unreleased
+## 6.0.9 - *2025-09-04*
 
 ## 6.0.8 - *2024-05-03*